Your '70 318 B-body *should*(you never know) have the '741'-series 8-3/4. If the C-body rear is an 8-3/4" (which it should be) you can at least use the center section. It will *probably* be an open diff with freeway gears, but should be the beefier 742 version. The housing is too wide and the spring perches are in the wrong location for your B, but as was said the C-body guys will snatch that stuff up. The large-pinion cases are getting expensive.
I know people love their 318s here, but in a B-body...do the 440 swap. With a stock 440 you have 470ish ft/lbs right out of the gate...
